panic on linux

[dvc94ch]

playing around with piet-gpu and parley using your piet-gpu integration. however I haven't gotten it to work yet. my guess is that since fount mentions it only supports windows and macos that this is currently expected.

MESA-INTEL: warning: Performance support disabled, consider sysctl dev.i915.perf_stream_paranoid=0

thread 'main' panicked at 'range end index 1 out of range for slice of length 0', /home/dvc/cloudpeer/parley/src/layout/line/greedy.rs:510:26
stack backtrace:
   0: rust_begin_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5
   1: core::panicking::panic_fmt
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14
   2: core::slice::index::slice_end_index_len_fail
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/index.rs:41:5
   3: <core::ops::range::Range<usize> as core::slice::index::SliceIndex<[T]>>::index
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/index.rs:240:13
   4: core::slice::index::<impl core::ops::index::Index<I> for [T]>::index
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/index.rs:15:9
   5: <alloc::vec::Vec<T,A> as core::ops::index::Index<I>>::index
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/alloc/src/vec/mod.rs:2496:9
   6: parley::layout::line::greedy::commit_line
             at /home/dvc/cloudpeer/parley/src/layout/line/greedy.rs:510:26
   7: parley::layout::line::greedy::BreakLines<B>::break_next
             at /home/dvc/cloudpeer/parley/src/layout/line/greedy.rs:222:12
   8: parley::layout::line::greedy::BreakLines<B>::break_remaining
             at /home/dvc/cloudpeer/parley/src/layout/line/greedy.rs:257:15
   9: parley::layout::Layout<B>::break_all_lines
             at /home/dvc/cloudpeer/parley/src/layout/mod.rs:110:9
  10: <piet_parley::ParleyTextLayoutBuilder as piet::text::TextLayoutBuilder>::build
             at /home/dvc/cloudpeer/parley/piet-parley/src/lib.rs:148:9
  11: engine_rs::render
             at ./main.rs:201:18
  12: engine_rs::main::{{closure}}
             at ./main.rs:93:17
  13: winit::platform_impl::platform::sticky_exit_callback
             at /home/dvc/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/platform_impl/linux/mod.rs:753:5
  14: winit::platform_impl::platform::wayland::event_loop::EventLoop<T>::run_return
             at /home/dvc/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/platform_impl/linux/wayland/event_loop/mod.rs:394:21
  15: winit::platform_impl::platform::wayland::event_loop::EventLoop<T>::run
             at /home/dvc/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/platform_impl/linux/wayland/event_loop/mod.rs:209:9
  16: winit::platform_impl::platform::EventLoop<T>::run
             at /home/dvc/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/platform_impl/linux/mod.rs:669:56
  17: winit::event_loop::EventLoop<T>::run
             at /home/dvc/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.26.1/src/event_loop.rs:154:9
  18: engine_rs::main
             at ./main.rs:50:5
  19: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[dfrg]

Yes, your guess is absolutely correct. Though I would have expected it to panic well before line breaking, perhaps when it was unable to select a fallback font. There's some code in there that ensures a single line/run always exists to support proper line and caret metrics for an empty layout and that's probably causing an odd interaction with the missing font leading to a panic at that point.

[dvc94ch]

the weird thing is that I am loading a font and only trying to render a latin string. shouldn't that work even if fount doesn't support a platform?

Never mind, apparently loaded fonts only work if the family is specified.